change TestPlugin from .java to .groovy to get rid of joint compilation problem
fix test after refactoring changes (state is not stored in mixins anymore)
use @ClassRule for @AfterClass rule that gets executed before mc cleanup in new solution
rename Book -> MCBook in this test
- tests have to be linked to grails-test-suite-uber in Eclipse because ASTs cannot be tested in same project as AST source
Run cleaner at closing time, deregister cleaner after usage
Add null checks
debug printlns when errors occur in test